Electrical properties of high-k Ta/sub 2/O/sub 5/ gate dielectrics on strained Ge-rich layers

Thin films of Ta/sub 2/O/sub 5/ have been deposited on strained Ge-rich layers using tantalum pentaethoxide [Ta(OC/sub 2/H/sub 5/)/sub 5/] by plasma enhanced chemical vapor deposition (PECVD) at low temperature. Electrical properties of the deposited samples have been measured using high frequency capacitance-voltage (C-V), conductance-voltage (G-V), and current-voltage (I-V) techniques. The fixed oxide charge density (Q/sub f//q) and interface state density (D/sub it/) are found to be 1.04 /spl times/ 10/sup 12/ cm/sup -2/ and 3.09 /spl times/ 10/sup 11/ cm/sup -2/ eV/sup -1/, respectively. The leakage current is observed to be dominated by Schottky emission (SE) at low electric field. The stress induced leakage current (SILC) is found to be negligible, indicating the good reliability of the deposited thin films.